The invention is related to roofing/cladding systems using elongate pans joined at their edges by hold-down clips and battens, the pans being straight or curved to cover flat, convex or concave surfaces.
Batten-style roofing/cladding systems are widely used for covering roofs, walls and similar structures. For simplicity, these systems will be referred to as roofing systems with the understanding that the invention is not so limited.
One of the problems with batten-style roofing systems is the ability to meet current engineering criteria for structural performance under negative loads, most often caused by wind. Negative loads tend to the lift the pans from the structure, thus placing a great deal of stress on the brackets holding the edges of the pans. To reduce costs of roofing systems using elongate pans having formed edges, such as batten-style systems, roll forming machines to produce the roofing components at the job site have been developed. With this technology, one or more roll forming machines are carried by a vehicle which also carries a large roll of material for each machine. This permits the pans and battens to be produced to exact lengths on site thus removing the need for lap joints. It also eliminates the cost of packaging non-nestable profiles as well. Freight damage is also eliminated with this type of system.
Another problem which must be addressed by batten-style roofing systems is thermal expansion and contraction. A roofing panel 150 feet long made from aluminum would expand and contract approximately 2 inches with a 100.degree. F. temperature change. Such expansion and contraction requires that the hold-down brackets permit the pans to slip longitudinally to accommodate this movement.
Other problems are created when roofing systems are used to cover curved structures. With batten-style, as well as standing-seam style, roofing systems, curved panels have generally been created by the use of crimping. The crimping not only is generally thought unsightly, it also degrades the surface integrity of the pans. Pans typically are prepainted or have other prepared surfaces for both aesthetic and corrosion reasons. However, crimping causes small cracks in the prepared surfaces for loss of surface integrity, thus permitting oxidation and discoloration of the panels.